South Dakota Statewide Rule
South Dakota state law: vehicle noise and muffler requirements
Key Facts
- Muffler statute
- SDCL 32-15-6
- Cutouts/bypasses
- Prohibited statewide
- State dBA cap
- None codified
- Local authority
- SDCL 9-29-1; SDCL 32-30
Summary
Per SDCL 32-15-6, every motor vehicle on a South Dakota highway must be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise, and no muffler cutout, bypass, or similar device may be used. Specific dBA limits, motorcycle exhaust standards, and engine-brake (Jake-brake) restrictions are set by municipalities under SDCL 9-29-1.
No person may drive a motor vehicle on a highway unless the motor vehicle is equipped with an exhaust system and a muffler both in good working condition and in constant operation to prevent excessive or unusual noise. Exhaust systems on passenger or passenger-carrying vehicles used on any highway shall discharge the exhaust fumes at a location to the rear of the vehicle body or direct the exhaust fumes outward from the side of the vehicle body at a location rearward of any operable side windows. Any motor vehicle equipped with side exhaust according to the original vehicle manufacturer specifications is exempt from the location requirements. A bus used for the purpose of carrying school children may discharge the exhaust on the left side in front of the rear axle. Exhaust systems on property-carrying vehicles used on any highway shall discharge the exhaust fumes at a point rearward of the passenger-carrying compartment. No person may use a muffler cut-out on any motor vehicle upon a highway. A violation of this section is a Class 2 misdemeanor.
Full Breakdown
SDCL 32-15-6 (Mufflers required) is the controlling statewide vehicle-noise statute: it requires every motor vehicle operated on a highway to be equipped with a muffler in good working order and in constant operation, and prohibits muffler cutouts, bypasses, or similar devices. The statute does not specify a dBA threshold and does not distinguish between motorcycles, cars, and trucks. Enforcement is by South Dakota Highway Patrol and local police as a Class 2 misdemeanor traffic offense. SDCL Title 32 Chapter 15 covers the statewide motor-vehicle equipment standards (lights, brakes, horns, mufflers).
Compression-brake (engine-brake / Jake-brake) restrictions, motorcycle decibel caps, and modified-exhaust enforcement at the local level are authorized under SDCL 9-29-1 (cities) and SDCL Chapter 11-2 (counties on county roads). Typical municipal vehicle-noise caps (set under local police power): 80 dBA at 50 ft for passenger cars and 96 dBA at 50 ft for motorcycles. The Sturgis Motorcycle Rally and broader SD motorcycle-tourism economy create a recognized political baseline against aggressive municipal motorcycle-exhaust enforcement during August.
Violations & Penalties
SDCL 32-15-6 violation: Class 2 misdemeanor traffic offense - up to 30 days in jail and up to a $500 fine. South Dakota Highway Patrol may issue an equipment-violation citation requiring repair and reinspection. Municipal vehicle-noise / engine-brake violations: typically civil fines of $50 to $250 per occurrence under local ordinance.
Frequently Asked Questions
Are loud exhaust pipes legal in South Dakota?
Can South Dakota cities ban Jake brakes?
Sources
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